Electric ignition devices for projectiles



Dec. 22, 1959 I s. ZAUGG I 2,918,007

ELECTRIC IGNITION DEVICES FOR PROJECTILES Filed Aug. 12, 1954 2 Sheets-Sheet 1 Fig.1

- INVEN T072 Samuel ATTORNEY Dec. 22, 1959 s. ZAUGG 2,918,007

ELECTRIC IGNITION DEVICES FOR PROJECTILES Fil ed Aug. 12, 1954 v 2 Sheets-Sheet 2 I NVENTOR Samuel BY n a-L- 119b Fig. 7.

ELECTRIC IGNITION DEVICES FOR PROJECTILES Samuel Zaugg, Soleure, Switzerland, assignor to Motha Treuinstitut, Vaduz, Liechtenstein, a corporation of Liechtenstein Application August 12, 1954, Serial No. 449,464

Claims priority application Switzerland August 31, 1953 4 Claims. 0. 102 70.2

It is known that in the case of some projectiles it is advantageous for the explosion to be produced as quickly as possible after percussion. Electric ignition devices for projectiles are known, comprising an electric generator composed principally of a coil traversed by a magnetic flux. The magnetic circuit through which this flux passes comprises a movable part adapted to move relatively to the stationary part of the said circuit at the moment of impact, so as to produce a rapid variation of the magnetic flux passing through the coil thereby inducing a voltage in the latter. This voltage is used to ignite the explosive charge carried by the projectile by acting in conjunction with a spark gap or an incandescent filament. In the devices known the movable part of the magnetic circuit must travel a distance of a few centimeters in order to produce the necessary charge igniting voltage. This necessary length of movement results in a delay between the time the projectile strikes its target and the time of ignition of the explosive charge. This delay is of particular consequence when the projectile strikes smooth metal structures at an oblique angle. In the latter case the projectile has frequently had time to rebound before the explosion of its charge and for this reason does not cause any damage to the plate.

The present invention has for its object to remedy this disadvantage. It relates to an electric ignition device for projectiles, characterised in that it comprises a condenser adapted to be connected in a circuit for'igniting the explosive charge in the projectile and an electricgenerator for charging the said condenser before the impact, the generatorbeing formed by a magnetic circuit comprising a permanent magnet and by a coil through which the magnetic flux of the said circuit passes, at least a portion of the magnetic circuit being movable in such a manner as to produce a variation of the magnetic field passing through the coil and to induce in said latter a voltage for charging the condenser before impact of the projectile, a contactor being provided for closing the charge igniting circuit for provoking the explosion of the projectile.

In the accompanying drawings are shown, by way of example, two forms of construction and of modifications of the electric ignition device for projectiles, forming the subject of the invention. I

Fig. 1 is a plan view of a first form of construction, the upper part being removed.

Fig. 2 is a vertical section on the line II-II of Fig.1.

Fig. 3 shows a detail of a cover. 7

Fig. 4 shows a diagram of the electric circuit of 'the device according to Figs. 1 to 3.

Fig. 5 shows a modification of the electric circuit.

Fig. 6 shows in section an electric detonator.

Fig. 7 is a view similar to Fig. 1 ofthe second form of construction.

Fig. 8 is a vertical section on the line VIII--Vl1I of Fig. 9 is a detail of Fig. 7 during the operation.

2 I I I l it ,1

second- Fig. 10 is a diagram of the electric circuit of the form of construction.

Fig. 11 shows a modification of this electric circuit.

With reference to Figs. 1 and 2 a condenser 1 is en-.

closed in a casing 2 with a generator adapted to charge it. At the bottom of the casing 2 is provided a flange 3, having a central hole of which the edge is provided with a tubular extension 4 extending in the direction of a second flange 5. Between the flanges 3 and5 is located a coil 6, wound on a support 7.

Two permanent magnets 8 and 9, each in the' form of a ring segment concentric to the coil 6, are placed on opposite sides of'the latter and are for the'purpose of creating a magnetic field of the general shape ofa toroidal casing surrounding thecoil. In Fig. 2, the 'polaritiesof the upper ends of the magnets 8 and 9 are of the same sign, for example south, while those of the lower ends of the 'said magnets are'of opposite polarity (north). The magnetic field created passes through the upper flange 5 in the direction of the centre of the coiljth'en through a movable cylindrical core .10, and the tubular extension 4 and returns to the magnets 8 and 9 through the lower flange 3. I

The movable core 10 can slide in 'a centraL- hole 'of the upper flange Sand through the tubularextension' 4 of the flange 3. A copper plate 11 is securedto the core '10 by its central portion,by meane t a ;nut 12 screwed on a rod 13. The two' ends of'the plate 11 bear against the edge of the central hole of the flange 5 in such a manner as to prevent accidentalmovement ofthe core 10 in the direction of the bottom of the casing}.

In principle, the device is mounted in the interiorof a projectile in such a manner that the axis of v.the cylinf drical core 10 is parallel to the direction of firing atthe moment of firing the shot and located in such a manner that the inertia of the core'10 tends to move the latter relatively to the flanges 3 and 5 in the direction ,of the bottom of the casing. When firing the shot, the accelera tion of the projectile is suflicient so that the force v of in ertia acting on the core 10 bends the plate 11 and'rnoves the said core 10 so as to lodge it in the tubular extension 4. This movement produces an increase in the resistance of the magnetic circuit between the extension 4.and the flange 5, so that the value of the magnetic field surrounding the coil 6 diminishes strongly, thus inducing a voltage in the latter. This voltage acts to charge the condenser 1, but, in order to prevent the latter discharging immediately afterwards into the coil 6, it is necessary to interrupt the connection betweenthese two elements byoperh ing contact 14, as shownin Fig. 4, as soon as the charging of the condenser has been effected. The projectile is shown in dotted lines with an ignition switch 31 having one contact thereof grounded at G and the other contact thereof normally spaced therefrom and-connected inthe condenser circuit. j w

This contact is formed by a spring blade 14, secured to an insulating part 15, the free end of said spring blade '14 hearing against the rod 13 of the core 10.- Oneend 16 of the coil 6 is connected directly to a terminal of the condenser 1, whilst the other end 17 of the;coil'is connected electrically to the blade 14, which is in contact with earth by means of the rod 13, The other terminal of the condenser is connected to earth by a wire 18, through the medium of a screw 19, which at the same time serves to secure the insulating part 15 to the flange acceleration tolodg e completely in the aforementioned tubular central section of the coil 6 defined by the flanges V Patented Dec. 22,- 1959;

3 ands. Thus, interruption of electric contact between the coil 6 and the condenser 1 is obtained when the latter is charged. It is to be observed that after movement of the core 10, the ends of the plate 11 engage under the upperwfian'ge against the edge of its central hole, so as to prevent the core 10 returning to its initial position and producingan accidental discharge of the condenser 1 into the coil 6..

In projectiles a muzzle security device is nearly always provided which is adapted to prevent exploding of the PL'Ojectile' in thecase of accidental impact just after leaving the gun. This security against accidental impact is Obtained in the device described by means of a retarding mechanism shown in Fig. 1. This mechanism comprises a toothed sector 20 of insulating material, pivoted at 21 and subjected to the action of a spring 22. The sector 20 is adapted to set in rotation a pivoted mass 23 through themedium of a gear train 24,25. All this mechanism ismounted on a plate "32 secured to'the upper face of the flange by two screws 33 and 34. An L-shaped contact blade 26 with two legs is secured by one leg to said sector 20 ofinsulating material and is connected electrically to the non-grounded terminal of the condenser 1. Its other leg is perpendicular to thesector 20 and extends toward ajcover 28. When the sector 20 makes a rotation in a clockwise direction (Fig. 1) under the action of its spring 22, the end of the leg of the blade 26, which is. perpendicular thereto, is adapted to. come into contact with a blade 27 mounted in the cover 28 closing the casing 2. Prior to the departure of the projectile, this rotation of the sector 20 is preventedby a pin 29 secured to the core 10. When the latter has sunk into the interior of the tubular part 4, the movement of the pin 29 releases the sector 20, which is adapted to pivot under the actionof the spring 22, its angularspeed being braked by reason of the inertia mass 23. The contact blade 27 then receives the voltage of the condenser 1 and ignition of the chaige of the projectile can be effected by means of an electric detonator.

Fig. 6 shows in section an electric detonator. This comprises a casing 36 in which is located a detonating material 37 and which is closed by a plug 38. Two conductors 30 and 31 are clamped between the casing and the plug and dip at their free ends into the detonating material. The voltage of the condenser 1 is applied to .the' conductors 30 and 31, for example by means of a time orimpact contactor (not shown) at the moment at which the explosion is to be produced, in such a man- 4 core may be provided with a central recess for reducing its weight.

The device shown in Figs. 7 to 9 only differs from that of Figs. 1 to 3 by the muzzle safety mechanism and similar parts of these two forms of construction bear the same reference numerals.

In this second form of construction, the muzzle safetymechanism is again providedwith a toothed sector 20 of insulating material, pivoted at 21 and subjected to the action of a spring 22. The sector 20 is adapted to set in rotation a pivoting mass 23 by means of a gear train 24, 25. All this mechanism is mounted on a plate 32 secured to the upper face of the flange 5 by two screws 33 and 34.

The sectorztl is provided with a metal part 40 which is connected electrically to the terminal of the condenser 1 which is not connected toearth. The part 40 has two fingers 41 and 42 directed perpendicularly to the sector 20. The finger 42 is connected electrically to a conductor, formed by a spring 43 which is wound around the inn and of which one end is bent and engaged in a transverse groove extending diametrically through the pin a 21. This end is in contact with a. blade 44 enclosed in er that a spark passes between the ends of the conduclots 30 and 31 and thus ignites the detonating material 37. j The safety adjustment of the projectile, that is to say the time during which the projectile cannot explode after firing the projectile, may be adjusted by varying the mass of the wheel 23 or by acting on the force of the spring 22. Further by varying the dimensions of the plate 11, it is possible to determine the value of the acceleration necessary to, allow for the functioning of the generator on the firing of the shot. i

" Fig. 5 shows a modification of the electric circuit of the device, in which a rectifying element 35 is connected between the condenser 1 and the coil G for replacing the contact 14 This rectifier 35 is selected so that the current in coil 6 can charge the condenser 1 and prevent passage of current in an inverse sense, that is, the condenser cannot discharge into coil 6. The core 10 may also be formed directly by a permanent magnet, the magnets 8 and 9 being then omittedand replaced by a sleeve of .ferro-magnetic material surrounding the coil 6 and closing the magnetic circuit externally, between the flanges 5 and 3. It will be understood that the retarding mechanism shown in Fig. 1 may be conceived in a different manner, in a way generally known technically, for example, by omitting the spring 22 and using, for replacing it, a mass subjected to centrifugal force, in the case of projectiles subjected to a rotary movement. The movable the cover 28. This blade 44 is adapted to be connected. as indicated in Fig. 10, to a grounded firing contact formed by a striker or firing pin 45, which forms one contact of an ignition switch in the condenser circuit.

Before the departure of the shot, a terminal of the condenser is connected to earth, whilst the other terminal is connected to the percussion contactor 45 by means of the parts 40, 43 and 44. When the sector 29 makes a rotation in a clockwise direction under the action of its spring 22, electrical connection is provided between the condenser 1 and the explosive charge ignition switch contact terminal 45 by reason of the elasticity of the spring 43 of which the end remains in contact with the finger 42 until the moment at which it is restrained by a pin 46 (Fig. 9). The sector 20continues its movement under the action of the spring 22 until the finger 41 comes into contact with a conductor 27 fitted into the cover 28. The conductor 27 then receives the voltage of the condenser 1 and ignition of the charge of the projectile may be obtained, for example, by an electric primer of the type of that shown in Fig. 6 and comprising two electrodes 30 and 31, between which is to pass a spark by reason of the closure of the striker or firing pin contact 45 at the moment of the impact.

The safety adjustment of the device, that is to say the time during which the projectile cannot explode after the departure of the projectile, may be adjusted by varying themass of the wheel or by acting on the force of the spring 22.

As shown clearly in the electric diagram of Fig. 10, the charge of the condenser 1 cannot be applied to the electric primer when the impact contactor is closed accidentally before the end of the duration of the safety adjustment. In fact, in this case, the condenser '1 is thus short-circuited and therefore discharged through 40, 43, 44 and 45 before the part 40 comes into contact with the blade Fig. 11 shows a more simple electric diagram, permit- .ting of obtaining the same result as that of Fig. 10. The retarding device, constituted by the sector 20, therefore controls a single contact 47 which is adapted to short circuit the electrical primer. The contact 47 is closed at the moment of firing the projectile and remains in this position up to the end of the safety adjustment, when it is opened by the sector 20. The contact 47 may, for example, comprise the elements 40, 42, 43 and 44 shown in Figs. 7 to 9, the elements 41 and 27 may therefore be eliminated. It will be seen thatif the contactor 45 is closed accidentally before opening the contact 47, the condenser 1 is discharged immediately, so that no voltage canbe applied between the electrodes 30 and 31 after opening the contact 47.

I claim: a

. 1. An electrical ignition device for projectiles having a grounded firing contact and an explosive charge, comprising, a condenser, an electric circuit having a contact normally spaced from said firing contact in the provision of an explosive charge ignition switch, said' condenser being connected in said circuit to ignite said explosive charge 'connectable therewith through said ignition switch upon impact of said firing contact portion thereof, a constant source of magnetic flux including an induction coil for charging said condenser, a magnetic circuit associated current in said coil to charge said condenser, a retarding mechanism, a locking pin carried bysaid movable core adapted to lock-said retarding mechanism prior to said momentof departure of said projectile, said locking pin being released upon the displacement of said movable core at said moment of departure of said projectile, said retarding mechanism being adapted to connect said condenser into the circuit, whereby said explosive charge is ignited through discharge of said condenser only after said ignition switch is closed by impact of said firing contact of said ignition switch.

2. A device as described in claim 1, wherein said circuit containing said explosive charge comprises an explosive primer, a contact means controlled by said retarding mechanism for shunting said condenser around said explosive primer for a predetermined time period follow-V ing said moment of departure of said projectile to cause a discharge of said condenser without ignition of said explosive charge if said ignition switch is closed during said predetermined period.

3. A device according to claim 1, wherein said magnetic circuit comprises a permanent magnet, a pair of flanges connected to said permanent magnet at the respective outer edges thereof and said flanges having inner edges respectively positioned adjacent the inner periphery of said induction coil, a central cylindrical passage formed by said inner edges of said flanges, a movable core magnetically connecting said inner edges of said flanges for completing said magnetic circuit mounted in said central cylindrical passageway for sliding motion therein, a deformable metal plate secured to one end of said movable core, one of said flanges providing a bearing surface for said deformable plate and having a downturned inner edge extending into said central cylindrical passage, whereby movement of said movable core is prevented prior to said moment of departure of said projectile.

I 4. A device according to claim 1 wherein said retarding mechanism comprises a movable sector having first and second contacts mounted thereon in operative relationship thereto, said first contact being adapted to shunt said condenser around the electric primer in the circuit containing said explosive charge for a predetermined time period after said moment of departureof said projectile and said second contact being adapted to close said circuit containing said explosive charge after said time period associated with said first contact has elapsed.

References Cited in the file of this patent UNITED STATES PATENTS 1,858,969 Ruhlemann May 17, 1932 2,486,362 OBrien Oct. 25, 1949 2,655,867 Jordan r Oct. 20, 1953 

